Swami Dayanand Saraswati wrote the Satyarth Prakash (The light of Truth).

About the Satyarth Prakash:

• As the great writer of this masterpiece, Swami Dayanand Saraswati was a symbol of ultimate morality and spiritualism and was a sage of standing.
• This book (Satyarth Prakash) is, indeed, and encyclopedia of the various contemporary social religious and political currents cross-currents and movements going on at the time of the writer’s life.
• To go it further, the writer has not spared the past events and guiding philosophies, which has polluted the human mind and deteriorated the man’s quest for true knowledge and right way of life.